A bathing system such as a spa typically includes a vessel for holding water, pumps, a blower, a light, a heater and a control for managing these features. The control usually includes a control panel and a series of switches which connect to the various components with electrical wire. Sensors then detect water temperature and water flow parameters, and feed this information into a microprocessor which operates the pumps and heater in accordance with programming. U.S. Pat. Nos. 5,361,215, 5,559,720 and 5,550,753 show various microprocessor based spa control systems. When in continuous use, the spa temperature is controlled by temperature sensors which measure the temperature of the water, and selectively activate a pump to circulate water, and a heater which raises the water to the temperature set by the user at the control panel.
Spa manufactures may make spas with similar control systems, but with differing power or requirements or specifications for the heater element or elements. In such circumstances, the manufacture may have to maintain inventory of various heaters with different specifications and construct spa systems with different current requirements with the different-rated heaters or heater elements, thereby incurring increased manufacturing costs.
Some spa systems utilize triacs for controlling the on/off condition of a heater. Triacs generate a certain amount of heat due to the current drawn through the triac, which may necessitate installing a heat sink for the triac, thereby incurring increased manufacturing costs.